1. Field of the Invention
The present invention relates to an image taking system, in particular to an image taking system that takes an image using two lens apparatuses.
2. Description of the Related Art
There have been developed image taking systems that obtain a stereoscopic image by taking parallax images corresponding to right and left eyes using two image taking apparatuses arranged side-by-side. The distance between the optical axis of the image taking apparatus corresponding to the right eye and the optical axis of the image taking apparatus corresponding to the left eye is designed basically to be 65 millimeters (which is approximately equal to the distance between the human eyes). However, in some cases, the shape and size of the image taking apparatuses may prevent the apparatuses to be arranged with a desired distance between the optical axes thereof. In view of this, an image taking system in which image taking apparatuses are arranged respectively above and behind a half mirror to take images has been developed.
FIG. 8 shows the outer appearance of the image taking system. FIG. 8 is a side view showing the system including lens apparatuses 1A and 1B having the same specifications, cameras 2A and 2B having the same specifications, a half mirror 3 and a camera platform 4 that supports the lens apparatuses 1A, 1b, cameras 2A, 2B and the half mirror 3. The lens apparatus 1A and the camera 2A are oriented horizontally, and beams coming from an object are transmitted through the half mirror 3 and enter the camera 2A through the lens apparatus 1A. The optical axes of the lens apparatus 1A and the lens apparatus 1B are arranged to be positioned in planes spaced apart from each other by approximately 65 millimeters (which is equal to the distance between the human eyes) in the direction perpendicular to the plane of the drawing sheet. The lens apparatus 1B and the camera 2B are oriented vertically, and beams coming from the object are reflected by the half mirror 3 and enter the camera 2B through the lens apparatus 1B. The lens apparatus 1A and the camera 2A are used to take a right eye image and the lens apparatus 1B and the camera 2B are used to take a left eye image, for example. Such a vertical arrangement enables flexible adjustment of the distance between the two image taking apparatuses on a half mirror surface without being affected by the shape and size of the image taking apparatuses.
Movable optical members such as magnification-varying mechanisms, focus adjustment mechanisms and image stabilization mechanisms in the respective two lens apparatuses used in such an image taking system for stereoscopic image are controlled in synchronization to make the optical conditions in the two lens apparatuses always identical to each other.
Japanese Patent Application Laid-Open No. 2007-33624 discloses a lens system for a stereoscopic camera in which two lens apparatuses use a vibration detector in common, and image stabilization units in the respective lens apparatuses perform image blur correction based on the vibration of the vibration detector, enabling a reduction in the difference in image stabilization characteristics between the two lens apparatuses.
In the prior art system disclosed in the aforementioned patent document, one vibration detector is used in common to detect the vibration of the two lens apparatuses, and each lens apparatus does not have a vibration detector. Therefore, each lens apparatus cannot perform image blur correction by itself. Nevertheless, a lens apparatus having an image stabilization function that can be used alone might sometimes be diverted for taking two-dimensional image. Therefore, it is desirable that the lens apparatus itself be equipped with a vibration detector to allow image blur correction by the lens apparatus alone. In other words, arrangement of a stereoscopic image taking system using two existing lens apparatuses for two-dimensional image taking each having an image stabilization function will eliminate the need for the preparation of special lens apparatuses. Thus, a versatile stereoscopic image taking system can be produced at low cost. However, in the case of the above-described image taking scheme in which a lens apparatus is arranged vertically with the use of a half mirror, the vibration detection axis of the vibration detector in the lens apparatus that is oriented vertically (i.e. the lens apparatus into which the beams reflected by the half mirror enter) will change. In consequence, image blur correction performed based on the vibration detected by the vibration detector equipped in the lens apparatus vertically oriented cannot be satisfactory.